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Flake-like nickel/cobalt metal-organic framework as highperformance electrodes for supercapacitors Xiaolong Zhang1 · Jiemei Wang2 · Xiang Ji2 · Yanwei Sui1 · Fuxiang Wei1 · Jiqiu Qi1 · Qingkun Meng1 · Yaojian Ren1 · Yezeng He1,3   · Dongdong Zhuang4 Received: 27 March 2020 / Accepted: 3 August 2020 © Springer Science+Business Media, LLC, part of Springer Nature 2020

Abstract Flake-like NiCo bimetal-organic framework (NiCo-MOF) is prepared via a simple one-step hydrothermal process. By combining the advantages of composition designing and distinctive micro/nanostructures, the flake-like NiCo-MOF constructed with two-dimensional (2D) nanosheets can be a promising candidate as active material for high-performance supercapacitors (SCs) in the aspect of enhanced specific capacitance and stability. In a three-electrode system using 1 m KOH as electrolyte, the fabricated flake-like NiCo-MOF electrode exhibits high-specific capacitance (1107.3 F g­ − 1 at 1 A ­g− 1), good rate performance (76.7% retention of its highest capacitance at 10 A ­g− 1) and long-term cycling stability (70.1% capacity retention after 5000 cycles at 15 A g­ − 1). Furthermore, an energy storage device based on reduced graphene oxide and flake-like NiCo-MOF shows a maximum energy density of 30.81 Wh ­kg− 1 at a power density of 749.9 W ­kg− 1 with high capacitance retention of ~ 85.3% (up to 5000 cycles at 15 A ­g− 1).

1 Introduction Nowadays, advanced energy systems such as supercapacitors, rechargeable battery and fuel cells are extensively used in portable electronics. Among them, the supercapacitors have attracted extensive attention due to its fast charging rate, long lifespan, high power density and admirable safety [1–3]. Among the electrode active materials of SCs, the transition metal Ni and related derivatives such as oxides [4],

* Yezeng He [email protected] * Dongdong Zhuang [email protected] 1



School of Materials and Physics, China University of Mining and Technology, Xuzhou 221116, People’s Republic of China

2



China National Heavy Duty Truck Group Co., Ltd, No 777 Huaao Road, Jinan, People’s Republic of China

3

The Jiangsu Province Engineering Laboratory of High Efficient Energy Storage Technology and Equipment, Xuzhou, People’s Republic of China

4

School of Material Science and Engineering, Jiangsu University, Jiangsu, Zhenjiang 212013, People’s Republic of China





sulfides [5, 6], phosphides [7, 8] and hydroxides [9, 10] are regarded as the most promising anode materials. Metal-organic framework (MOF) materials have drawn widespread attention in recent years due to the porous characteristics, which not only possess plenty and easily accessible metal structure sites, but also provide three-dimensional (3D) channels for fast material transport [11, 12]. In a wide variety of MOFs, porous nickel-based MOF (Ni-MOF) as a novel electrode material for supercapacitors has become a new research hotspot [13, 14]. The unique nanoporous structure makes Ni-MOF possess excellent electrochemical properties than bulk one